The way I characterize this finding that we published in Nature is, imagine if you’re looking at a very high, seemingly unscalable cliff. And so far, efforts to climb it have not reached the top. What this work does is basically show a path. We still have to climb a cliff, but now we have a path we can follow.

We’ll talk to Picker about why that cliff has seemed unscalable in the past — the particular challenges that HIV offers to immunologists, in other words — and what obstacles he sees on the new path.

By chance, this vaccine news nearly coincided with an announcement from the other spectrum of HIV research. A major study found that people with HIV are much less likely to infect others if they take antiretroviral drugs. In fact, the study was halted four years early because the interim results were so stark: of the 28 cases of linked HIV transmission, 27 of them were among couples in which the HIV-infected partner delayed antiretroviral treatment.

What will these two findings mean for the future of HIV/AIDS research and treatment?